Clamping devices

ABSTRACT

A clamping device comprising two clamping jaws each slidable along a shank to a desired clamping location on the shank and then engaging with the shank and exerting a clamping force which is reacted through the shank. Each clamping jaw comprises an elongated jaw member having a shank receiving aperture at one end portion thereof and a clamping pad at the other end portion thereof for exerting the clamping force on a workpiece. Each jaw member carries a first contact pad for frictional engagement with a side of the shank adjacent the clamping pad and a second contact pad for frictional engagement with the side of the shank remote from the clamping pad at a position along the shank in the direction of said clamping force from the first clamping pad. The contact pads have a surface for engaging the shank incorporating projections of substantial crest radius such that in use the projections elastically deform the surface of the shank into depressions corresponding to the crests of the projections. At least one clamping jaw is also provided with means for moving its second contact pad in a direction towards the shank to thereby tend to pivot the jaw member to produce the clamping force on the workpiece.

[ Sept. 11, 1973 CLAMPING DEVIICES [76] Inventors: David John Taylor, 6Overtons Close; Aris Medals, 8 Overtons Close, both of Redford Semele,Leamington Spa, England [22] Filed: Mar. 16, 1971 [21] Appl. No.:124,882

. [30 Foreign Application Priority Data Mar. 23, 1970 Great Britain14,009/70 Oct. 1, 1970 Great Britain..... 46,670/70 [52] U.S. Cl269/203, 269/238, 269/240, 269/321 ME [51] Int. Cl E2511; 1/02, 1/10[58] Field of Search ..269/166-17L5, 189,

[56] References Cited 7 UNITED STATES PATENTS 1,187,109 6/1916Stevernagel 269/204 1,639,561 8/1927 Hargrave 269/1715 3,149,860 9/1964Hallesy 285/382 X FOREIGN PATENTS OR APPLICATIONS 838,619 12/1938 France269/204 Primary ExamineF-Harold D. Whitehead Assistant ExaminerNeilAbrams Att0meyKenway, Jenney & Hildreth [57] ABSTRACT A clamping devicecomprising two clamping jaws each slidable along a shank to a desiredclamping location on the shank and then engaging with the shank andexerting a clamping force which is reacted through the shank. Eachclamping jaw comprises an elongated jaw member having a shank receivingaperture at one end portion thereof and a clamping pad at the other endportion thereof forexerting the clamping force on a workpiece. Each jawmember carries a first contact pad for frictional engagement with a sideof the shank adjacent the clamping pad and a second contact pad forfrictional engagement with the side of the shank remote from theclamping pad at a position along the shank in the direction of saidclamping force from the first clamping pad. The contact pads have asurface for engaging the shank incorporating projections of substantialcrest radius such thatin use the projections elastically deform thesurface of the shank into depressions corresponding to the crests of theprojections. At least one clamping jaw is also provided with means formoving its second contact pad in adirection towards the shank to therebytend to pivot the jaw member to produce the clamping force on theworkpiece.

7 Claims, 5 Drawing Figures PATENTED SEP 1 1 I973 suEEf 1 HF SEPI 1 maPATENTED Y 3,758,100 sum 2 0r 3 t CLAMPING IDEVMIES BACKGROUND OFTHEINVENTION The invention relates to clamping devices and is particularlyconcerned with clamping jaws for sliding along a shank to a desiredclamping location and then is concerned with individual clamping jaws aswell as with complete clamping assemblies.

A complete clamping assembly normally comprises a reactive clamping jawwhich remains fixed while clamping pressure is being applied, and anactive clamping jaw at least part of which is forced towards theworkpiece in order to clamp the workpiece. Throughout the specificationthe words active and reactive as applied to clamping jaws have themeaning given to them in this paragraph.

Currently one method of anchoring an active jaw on a'shank consists ofpivotally mounting the active jaw at a position intermediate its endportions about one of a series of rack teeth arranged along a side edgeof the shank, the jaw being angularly motivated about the pivot bymechanical means such as a screw in the jaw, the end of which bearsagainst the opposite side edge of the shank. Rotation of the screw inone direction causes rotation of the jawto apply a clamping force. Thisform of cramp is commonly referred to as the CARVER cramp.

One of the drawbacks of this arrangement is that, due to the spacingbetween each tooth on the shank, initial coarse adjustment of theposition of the active jaw, governed by the positions of the teeth isoften insufficient to bring the movable jaw into contact with theworkpiece or really close to the workpiece with the result thatexcessive movement of the screw (and therefore the movable jaw) isnecessry to achieve the final clamp, hence the arrangement is unsuitableas a quick action mechanism. Another disadvantage is the cost incurredin forming the rack teeth.

As an alternative, it has been proposed to construct the active jaw witha collar or ring near one end which embraces the shank and to support aclamping pad on a screwed shaft located in a threaded bore near theother end of the jaw; the clamping pad representing the operating faceof the jaw.

Initial course adjustment of the jaw is by sliding it along the shank.On subsequent rotation of the screwed shaft in one direction, to forcethe clamping pad against the workpiece, a reaction is produced whichforces the jaw angularly relative to the shank, causing one set ofdiagonally opposed corners of the collar or ring to frictionally gripopposed faces of the shank to produce a reactive force which governs thefinal clamp between the jaws.

In this construction, the efficiency of the locking action on the shankincreases with an increase in the ratio between the effectiveaxiallength of the collar, i.e. the distance in a direction along theshank between the diagonally opposed corners of the collar and thedistance between the opposed faces of the shank. However, the effectiveaxial length of the collar cannot be reduced to a small distance sincethe jaw must be capable of withstanding the stresses set up inoperation. These two conflicting requirements detract from the value ofthis design. I

Another disadvantage of this type of clamp is that the application of avibratory or impact generated motion to the clamp or to the workpiece onwhich it is engaged will cause the frictional grip of the collar or ringto be overcome, and the resultant movement of the collar or ring underthe effect of the resilience of the material will result in a reductionin or total loss of clamping force.

BRIEF SUMMARY OF THE INVENTION A primary object of the present inventionis to provide an improved form of clamping device. Particular objectsare to provide a clamping device which is readily adjustable, whichoperates by virtue of frictional engagement between a shank and aclamping jaw and which remains effective in a vibratory environone endportion thereof and a clamping pad at the other end portion thereof forexerting a clamping force on a workpiece in one longitudinal directionof the shank, a first contact pad for frictional engagement with theside of the shank adjacent the clamping pad and a second contact pad forfrictional engagement with the side of the shank remote from theclamping pad at a position along the shank in the direction of saidclamping force from the first contact pad, the first contact pad havinga surface for engaging the shank incorporating projections ofsubstantial: crest radius such that in use the projections elasticallydeform the surface of the shank into depressions corresponing to thecrests of the projections on the first contact pad.

Preferably both contact pads have surfaces for engaging the shankincorporating projections of substantial crest radius such that in usethe projections elastically deform the surface of the shank intodepressions corresponding to the projections on both of the contactpads.

As a result of the nature of the frictional engagement between the firstcontactpad or both contact pads and the shank an exceptionally goodfrictional engagement between the clamping jaw jaw the incorporate canbe achieved without damaging the surface of the shank. The use ofconventional teeth in place of radiused projections would result insubstantial damage to the surface of the shank after extensive use as aresult of per manent deformation of the shank surface by the teeth. Ithas been found that a sufficient frictional engagement can be achievedto render the clamping jaws effective even in a vibratory environment.

The clamping force may be exerted on the jaw as a reaction force byforcing the workpiece againt the jaw in which case the jaw is a reactionjaw. Alternatively the member may provision a mechanism for forcing theclamping pad towards aworkpiece when the jaw is assembled on a shank inwhich case it is an active jaw.

For this purpose the first contact pad may be in a fixed position withrespect to the jaw member and the second contact pad may be movable withrespect to the jaw member, force exerting means being provided forforcing the second contact pad towards the shank with respect to the jawmember. As this movement results in a tilting of the jaw member, thesecond clamping pad tends to move in an arc with respect to the jawmember and provision to permit this movement should be provided.

Preferably both contact pads are free to pivot with respect to the jawmember so that in operation they become accurately aligned with thesurfaces of the shank and in the case of an active jaw they maintainthis accurate alignment despite pivotal movement of the jaw member.

Preferably the means to provide movement of the second contact pad withrespect to the jaw member comprises a link pivoted at one end about thecentre of pivotal movement of the first clamping pad, and at the otherend pivotally supporting the second clamping pad.

For practical convenience the link may be formed as two parallel linkmembers, one at each side of the jaw. The link serves to guide thesecond contact pad to ensure that it adopts a position where aneffective clamping action occurs. It has been found by experience thatin the absence of such a'link there is a tendency for the active jaw asva whole to slide along the shank away from the workpiece during aclamping operation due to the reaction from the clamping force betweenthe clamping pad and the workpiece before a substantial frictionalengagement becomes established between the contact pads and theworkpiece. This appears to be because the frictional engagement betweenthe contact pads and the shank tends to be disturbed by the initial partof the clamping operation. However, once a substantial clamping forcehas built up the substantial frictional forces hold the jaw with respectto the shank, ir-

'. respective of the provision of the link. Thus the link is preferablyprovided with a small amount of free play so that it becomes free once asubstantial clamping force has been established and plays no furtherpart in the operation of the clamping device.

In many situations an active clamping jaw and a reactive clamping jawboth in accordance with the invention will be used together inconjunction with a single shank. However, a reactive jaw in accordancewith the invention or an active jaw in accordance with the invention maybe used individually in some circumstances. For example, an active jawmay be used in conjunction with a fixed shank to exert a clamping forceon a workpiece to clamp it against a fixed support. A reactive jaw on ashank may be used in a jig to support part or all of a component to beoperated on, irrespective of whether the workpiece is clamped againstthe reactive jaw by an active jaw in accordance with the invention.

According to a further aspect of the invention there is provided anactive clamping jaw for sliding along a shank to a desired clampinglocation and then exerting a clamping force which is reacted through theshank, the jaw comprising an elongated jaw member with a shank receivingaperture at one end portion thereof and a clamping pad at the other endportion thereof for exerting a force on a workpiece in one longitudinaldirection of the shank, a first contact pad for frictional. engagementwith the side of the shank adjacent the clamping pad and a secondcontact pad for frictional engagement with the side of the shank remotefrom the clamping pad and a second contact pad for frictional engagementwith the side of the shank remote from the clamping pad at a positionalong the shank in the direction of said clamping force from the firstcontact pad, the first contact pad being pivoted to the jaw member andthe second contact pad being guided by guide means to be free to move onan arcuate path with respect to the jaw member centred on the pivot ofthe first jaw member, lateral force exerting means for exerting a forceon the second contact pad towards the shank with resepct to the jawmember such that during a clamping operation the two contact padsfrictionally engage the shank and the jaw member is caused to moveangularly with respect to the contact pads to apply the clamping forceat the clamping pad.

According to another aspect of the invention there is provided a clampassembly comprising two jaws each having a clamping pad and means forrelatively forcing the clamping pads together, the clamping pads eachcomprising a rotatable work-engaging portion, the two clamping padsbeing aligned or alignable such that the rotatable portions are free torotate about a common axis.

By this means a workpiece clamped between the two rotatable portions canbe rotated without disturbing the clamping action. The sameconsiderations apply to rotation of a clamping device with resepct to aworkpiece.

Relative rotation between a workpiece and a clamping device can occur asa result of applied vibrations and thus utilisation of this latteraspect of the invention is an important contributory factor in making aclamping device effective in a vibratory environment.

BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION OF THE PREFERREDEMBODIMENT The clamping device shown in FIGS. 1 to 4 incorporates ashank 11, an active clamping jaw 12 and a reactive clamping jaw 13.

The shank 11 is a length of standard rolled steel strip and may, forexample, be 1% inches by /4 inch strip. As this standard steel strip isreadily available, it is possible to use a variety of lengths of shankin conjunction with the same active and reactive jaws, to form either acompact clamping device or a clamping device with a large distancebetween the jaws. Although it is envisaged that clamping devicescomprised by one active jaw, one reactive jaw and one shank may be soldand used as a unit, many users will require to purchase a series ofactive and passive jaws and use these in conjunction with separatelypurchased steel strip. For example, if the clamping device is to beincorporated into a jig the jig may be built up from suitablerectangular steel strip with a series of active and reactive jawsapplied at suitable locations.

The reactive jaw 13 is constructed primarily of two sheet steelpressings 14 and 15 which are secured together with a space therebetweenby four transverse pins 16. The space between the two pressings 14 and15 is a little more than the thickness of the shank 11 and most of thisclearance is taken up by a series of dimples 17 pressed inwardly of theperssings 14 and 15. These dimples guide the reactive jaw during slidingmovement between the jaw and the shank. The two pressings 14 and 15together with the pins 16 form a jaw member.

At one end portion of the reactive jaw member there is a clamping pad 18which will be described in more detail hereinafter.

At the end portion of the reactive jaw member remote from the clampingpad 18 there are two contact pads 19 and 21 which are supported withrespect to the jaw member by means of transverse pivot pins 22 and 23respectively. The pivot pins 22 and 23 may be located axially bysuitable spring clips 20. The first contact pad 19 is positioned on thelower part of the depth of the jaw in the configuration shown in whichthe clamping pad 18 exerts a downward clamping force on the workpiece.In this configuration the second contact pad 21 is, in effect, above thecontact pad 19 although a portion of the contact pad 21 does extend downto the level of the pad 19.

FIG. 4 shows the contact pad 19 on a larger scale and shows details ofthe surface thereof which, in use, engages the shank 1'1. This shankengagement surface 24 incorporates a series of lateral ribs orprojections 25. These projections are shown diagrammatically and are notto scale. For engagement with mild steel it has been found that suitabledimensions are as follows:

Pitch between adjacent projections: 0.060 inches Depth of projectionsfrom crest to root: 0.10 inches Radius of curvature of crests: 0.10inches or 0.15

inches These dimensions, and particularly the pitch and the depth of theprojections are not critical and any dimensions generally of this ordershould be suitable. The important aspect of these dimensions is that theradius of curvature of the crests should be such that in use the surfaceof the shank 11 is deformed elastically by ongagement therewith of theprojections. If the radius of curvature of the crest of the projectionsis too small, exceptionally high surface loadings would occur, resultingin permanent deformation of the shank surface. On the other hand, if theradius of the projections is unduly large, then the extent of thesurface deformation will be very limited and the frictional forcegenerated between the shank and the contact pads may be insufficient toprovide an effective clamping action, particularly in a vibratorenvironment. The material of the contact pads should be sufficiently hadto prevent any substantial deformatio of the contact pad in use. Highgrade tool steel or other materials normally. used for cutting tools.would be suitable.

' Although the above description of a contact pad has, made particularreference to the contact pad 19 the contact pad 21 is similar to thecontact pad 19 and also the cpntact pads of the active jaw 12 alsocorrespond.

Returning to FIGS. 1 and 2, the contact pad 19 is so arrange withrespect to one of the transverse pins 1d that the angular rotation ofthe contact pad about its pivot pin 22 is restricted. This ensures thatthe surface of the contact pad which engages the surface of the shank 11is always the surface 24. v

The second contact pad 21 has a shank engaging surface 26 correspondingto the shank engaging surface 24. This surface 26 is recessed at 27 toaccommodate one of the transverse pins 16 with a clearance. A singleleaf spring 28 engages the'rear face of the contact pad 21 and urges ittowards the shank 11. When the shank is removed the pin 16 in the recess27 prevents the spring 28 from moving the contact pad 21 through asubstantial distance. The spring 28 engages over a further transversepin 16 and also engages with a pivot pin 29 associated with the clampingpad 18.

The clamping pad 18 will now be described in more detail with referenceto FIGS. 2 and 3. The clamping pad comprises a pressed steel yoke 31which has two upwardly extending limbs which pass one each side of theouter ends of the plates 14 and 15. The pivot pin 29 passes throughaligned holes in the yoke 31 and the plates 14 and 15 in order topivotally mount the yoke about a transverse axis on the jaw member. Thelower part of the yoke joining the two limbs is flat and incorporates acentral circular hole 32. A freely rotatable clamping disc 33 is mountedfor rotation in the hole 32 by means of an upwardly extending pin 34.The pin 34 has a head 35 of the same diameter as the general diameter ofthe pin 34, the head being formed by a waist 36 in the pin immediatelybelow the head. A spring clip 37 which is located by the pivot pin 29engages with the waist 36 and thus holds the pin 34 of the clamping disc33 in the hole 32. However, the clamping disc may be removed by astraight axial pull and then can be snapped into position again.

In many specialised clamping operations it is desirable to exchange theclamping disc for an alternative work engaging device adapted to theshape of the workpiece. The simple clip-in and clip-out action of theclamping disc clamping this exchange to be effected in a very simplemanner.

The pivot pin 29 has a central portion of slightly reduced diameter andthe spring 28 engages this reduced diameter portion so that the spring28 locates the pin 29 laterally.

The active jaw 12 corresponds in many respects to the reactive jaw 13.Where individual parts correspond closely they have been given referencenumbers corresponding to those of the reactive jaw but with the prefix Iadded to these reference numerals. Thus the reactive jaw incorporatestwo pressings 114 and 115 joined by a series of pins 116. There is aclamping pad 118. Similarly there are two contact pads 119 and 121.

The fundamentaldistinction between the active and the reactive jawsconcerns the mounting of the contact pad 119. This contact pad 119 isfree to move its position with respect to the jaw member. The twostampings 114 and 115 incorporate arcuate clearance slots 101 whichreceive a pin 102 which passes throughthe contact pad 119. A pair oflinks 103 pivoted about the pivot pin 123, of the contact pad 121 arealso pivoted to the pin 102 so that this pin is free to move on an arccentred about the pivot pin 123. The arcuate slots 101 do not come intocontact with the pin 102 except at the extremities of its movement. Arectangular nut 104 is supported in two corresponding rectangularapertures in the pressings 114 and 115 at a position behind the contactpad 119 and this nut carries a manually operable screw which is threadedin the nut 104 and in use bears against the rear surface of the contactpad 119. This rear surface of the contact pad 119 is in the form of avertical arcuate groove and the end of the bolt 105 which runs in thisgroove has a corresponding part spherical surface of slightly smallerradius than the groove. This ensures that contact between the bolt 1105and contact pad 119 does not prevent relative vertical movement betweenthese components and that forces between these components aresubstantially within a vertical central plane.

The operation of the clamping device will now be described, startingwith the reactive jaw 13. When a workpiece is engaged between the twoclamping pads 18 and 118' the pad 118 can be caused to exert a clampingforce as will be described hereinafter. This force is reacted by theclamping pad 18 of the reactive jaw. A vertical upward force on theclamping pad 18 in the configuration shown in the drawing tends to.rotate the reactive jaw about its mounting on the shank 11 which, inturn, generates substantial pressure forces between the contact pads andthe shank as a reaction against the applied moment. These substantialpressure forces result in limiting friciton forces in a direction alongthe shank which are substantially greater than the force applied to theclamping pad 18 with the result that the reactive jaw maintains itsposition irrespective of the load applied to the clamping jaw. Thespring 28 results in a slight'initial gripping of the shank by thecontact pads so that the reactive jaw will maintain its position evenwithout any applied load. When atypical clamping load has been appliedthe reaction forces between the shank and the contact pads aresufficient to cause the projections 25 (see FIG. 4) to be pressed intothe surface of the shank and thereby improve the frictional grip. Thedeformation of the shank is of an elastic nature so that the surface ofthe shank is not damaged. Due to the fact that the contact pads arepivotally mounted, the forces between the contact pads and the shank areevenly distributed over the surface.

The active jaw could be used as a reactive jaw and in such a case theoperation would be as described above for the reactive jaw. However, theprimary intended use of the active jaw is to enable a clamping force tobe applied by movement of the clamping pad 118 in a direction towardsthe workpiece. In order to effect this clamping operation the screw 105is rotated in such a direction that it tends to force the contact pad119 towards the shank l1. Considered another way, this screwingoperation tends to draw the upper left hand part (in the drawing) of theactive jaw member towards the left in the drawing, away from the shank.Thus the whole jaw member tends to rotate about the pivot pin 123thereby causing the clamping pad 118 to press against the workpiece.Pressure and friction forces between the contact pads 119 and 121 andthe shank 11 corresponding to the similar forces of the reaction jawtend to develop as a result of the rotation of the jaw member and thecreation of a force on the workpiece by the clamping pad 118. Theclamping force can be increased by further rotation of the screw 105 andthe resulting increase in clamping force on the workpiece results incorresponding increasing forces between the shank and the contact pads119 and 121.

During initial tightening of the screw 105 to apply an initial clampingforce there would, in the absence of the links 103, be a tendency forthe active jaw 12 to slide bodily down the shank 11 as a reaction to theinitial clamping force on the workpiece before any positive engagementhad been established between the contact pads and the shank. It isbelieved that the reason for this is that the balance between theclamping force and the frictional forces can be upset during the initialpart of the clamping operation by practical factors such as slightirregularities in the surfaces between the screw and the contact pad119. However, the provision of the links 103 tends to hold the contactpad 119 in its desired location so that it is a simple matter toestablish the required clamping forces. The links 103 do not take anysubstantial part of the main clamping load and due to the fact that theyhave slightly oversize holes for engaging in the appropriate pins theselinks tend to become free and take no load whatsoever as the clampingforce is increased.

A clamping device as shown in FIGS. 1 to 4 remains effective in avibratory environment despite the fact that it relies on frictionalforces. The nature of the engagement between the contact pads and theshank has been found to stand up to vibration without any tendency forthe clamping forces to be reduced by sliding of one or other of theclamping jaws along the shank. In addition, any vibration tending torotate the workpiece is free to rotate the workpiece due to the natureof the clamping pads and this rotation does not tend to twist theworkpiece out of the clamping device.

An alternative application of an active clamping jaw is shown in FIG. 5.A shank 51 is secured to a work table 52 by means of a bracket 53. Anactive jaw 54 is positioned on the shank 51. This active jaw may be usedto clamp a workpiece of any height within the limits of the shank 51 tothe work table 52.

Active and reactive jaws in accordance with the invention and asdescribed in detail above may be used in a wide variety of applicationsin conjunction with suitable shanks.

We claim:

1. An active clamping jaw for sliding along a shank to a desiredclamping location and then exerting a clamping force which is reactedthrough the shank, the jaw comprising:

an elongated jaw member,

jaw member portions defining a shank receiving aperture at one endportion of the jaw member,

a clamping pad secured to the opposite end portion of the jaw member forexerting a force on a workpiece in one longitudinal direction of theshank, a first contact pad pivotally mounted on said jaw member andarranged for frictional engagement with a side of the shank adjacent theclamping pad,

a second contact pad carried by said jaw member and arranged forfrictional engagement with the side of the shank remote from theclamping pad at a position along the shank in the direction of saidclampin force from the first contact pad,

guide means operatively interconnecting the second contact pad to thejaw member such that it is free to move on an arcuate path with respectto the jaw member centred on the pivot of the first jaw member,

lateral force exerting means carried by the jaw member and arranged forexerting a force on the second contact pad towards the shank withrespect to the jaw member,

the arrangement being such taht during a clamping operation the twocontact pads frictionally engage the shank and the jaw member is casuedto move angularly with respect to the contact pads to apply the clampingforce at the clampin pad.

2. A clamping jaw for sliding along a shank to a desired clampinglocation and then engaging with said shank, and exerting a clampingforce which is reacted through szid shank, said jaw comprising:

an elongate jaw member,

a clamping pad secured atone end portion of said jaw member for exertinga clamping force on a work piece in one longitudinal direction of saidshank,

a first contact pad and a second contact pad carried at the -oppositeend portion of said jaw member, said contact pads defining between thema shank receiving space, a surface of said first contact pad beingarranged for frictional engagement with a side of said shank adjacentsaid clamping pad and said second contact pad being arranged forfrictional engagement with the side of said shank remote from saidclamping pad at a position along said shank in the direction of saidclamping force fromsaid first contact pad, and one of said contact padsbeing mounted on said jaw member for pivotal movement about an axisfixed with respect to said jaw member, and the other of said contactpads being movably mounted on said jaw member,

being connected between said that of said contact pads and said jawmember for moving said other of said contact pads relative to said jawmember in a direction towards said shank and thus pivoting said jawmember with clamping to said shank for applying clamping force to saidworkpiece, said jaw member pivoting about said axis about which said oneof said contact pads is mounted for pivoting with respect to said jawmember.

3. A clamping jaw as claimed in claim 2 wherein said other of saidcontact pads is mountedfor pivoting relative to said jaw member so thatin use it is permitted to align itself accurately with said shank.

4. A clamping jaw as claimed in claim 2 and including a springoperatively connected between said jaw member and said one contact padin one rotational direction to enable said one contact pad to grip saidshank between it and said other contact pad whereby even in the absenceof a clamping force said clamping jaw retains itself in a fixed positionon said shank.

5. A clamping jaw as claimed in claim 1 wherein said guide meanscomprises a link pivoted at one end thereof to the jaw member and at theother end thereof to the second contact pad tocontrol the movement ofthe second contact pad with respect to the jaw member.

6. A clamping jaw as claimed in claim 5 in which the first contact padis pivoted to the jaw member and in which the link is pivoted to thepivotal axis of the first contact pad. h

7. A clamping assembly comprising a shank and two clamping jaws forsliding along said shank to desired clamping locations and then engagingwith said shank and exerting a clamping force which is reacted throughsaid shank, each of said jaws comprising:

an elongated jaw member,

a clamping pad secured at one end portion of said jaw member forexerting a clamping force on a work piece in one longitudinal directionof said shank,

a first contact pad and a second contact pad carried at the opposite endportion of said jaw member, said contact pads defining between them ashank receiving space, a surface of said first contact pad beingarranged for frictional engagement with a side of said shank asjacentsaid clamping pad and said second contact pad being arrangedforfrictional engagement with the side of said shank remote from saidclamping pad at a position along said shank in the direction'of saidclamping force from said first contact pad, one of said contact padsbeing mounted on said jaw member for pivotal movement about an axisfixed with respect to said jaw member, and the other of said contactpads being movably mounted on said jaw member, means for being connectedbetween said other of said contact pads and said jaw member for movingsaid other of said contact pads relative to said jaw member in adirection towards said shank and thus pivoting said jaw member withrespect to said shank for applying clamping force to said work piece,said jaw member pivoting about said axis about which said one of saidcontact pads is mounted for pivoting with respect to said jaw member,said clamping pad of each of said jaws including a work engagingportion, said clamping pad being pivotally connected to the jaw memberfor movement about an axis transverse to the length of the jaw memberand to the length of the shank and said work engaging portion beingrotatable with respect to said clamping pad.

7 3 UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No. 3,758,100 Dated September ll 1973 Inventor(s) David John Taylor and AriaMednis It is certified that error appearsin the ebove identificd patentand that said Letters Patent are hereby corrected as shown below:

E01. 2 line 24, change "reduced to reacted I r line 38, change"corresponing" to corresponding line 49, cancel jaw the incorporate" andinsert and the shank line 62, cancel the member may provision" andinsert the jaw may incorporate Col. 4, line 10, change resepct torespect line 26, change "resepc't to respect Col. 5, line 7, change "perssings" to pressings line 55, change lvibrator to vibratory line 56,change "had" to hard 7 line 57, change deformatio" to deforr nation line63, change "cpntact" to contact line 65, change "arrange" to arrangedCol. 8, line 67, (claim 1) change "'taht to that. Col. 9, line 1, (claiml) change casued" to 7 caused Col. 9, line 31, (claim 2) cancel"clamping" and insert respect Col. 10, line 23, (claim 7) change"asjacent" to adjacent Signed and sealed this 2nd day of April l97h.

(SEAL) Attest:

EDWARD IVLFLETCHER, JR. c MARSHALL DANN p a ttestin Officer Commissionerof Patents

1. An active clamping jaw for sliding along a shank to a desiredclamping location and then exerting a clamping force which is reactedthrough the shank, the jaw comprising: an elongated jaw member, jawmember portions defining a shank receiving aperture at one end portionof the jaw member, a clamping pad secured to the opposite end portion ofthe jaw member for exerting a force on a workpiece in one longitudinaldirection of thE shank, a first contact pad pivotally mounted on saidjaw member and arranged for frictional engagement with a side of theshank adjacent the clamping pad, a second contact pad carried by saidjaw member and arranged for frictional engagement with the side of theshank remote from the clamping pad at a position along the shank in thedirection of said clampin force from the first contact pad, guide meansoperatively interconnecting the second contact pad to the jaw membersuch that it is free to move on an arcuate path with respect to the jawmember centred on the pivot of the first jaw member, lateral forceexerting means carried by the jaw member and arranged for exerting aforce on the second contact pad towards the shank with respect to thejaw member, the arrangement being such taht during a clamping operationthe two contact pads frictionally engage the shank and the jaw member iscasued to move angularly with respect to the contact pads to apply theclamping force at the clampin pad.
 2. A clamping jaw for sliding along ashank to a desired clamping location and then engaging with said shankand exerting a clamping force which is reacted through szid shank, saidjaw comprising: an elongate jaw member, a clamping pad secured at oneend portion of said jaw member for exerting a clamping force on a workpiece in one longitudinal direction of said shank, a first contact padand a second contact pad carried at the opposite end portion of said jawmember, said contact pads defining between them a shank receiving space,a surface of said first contact pad being arranged for frictionalengagement with a side of said shank adjacent said clamping pad and saidsecond contact pad being arranged for frictional engagement with theside of said shank remote from said clamping pad at a position alongsaid shank in the direction of said clamping force from said firstcontact pad, and one of said contact pads being mounted on said jawmember for pivotal movement about an axis fixed with respect to said jawmember, and the other of said contact pads being movably mounted on saidjaw member, being connected between said that of said contact pads andsaid jaw member for moving said other of said contact pads relative tosaid jaw member in a direction towards said shank and thus pivoting saidjaw member with clamping to said shank for applying clamping force tosaid workpiece, said jaw member pivoting about said axis about whichsaid one of said contact pads is mounted for pivoting with respect tosaid jaw member.
 3. A clamping jaw as claimed in claim 2 wherein saidother of said contact pads is mounted for pivoting relative to said jawmember so that in use it is permitted to align itself accurately withsaid shank.
 4. A clamping jaw as claimed in claim 2 and including aspring operatively connected between said jaw member and said onecontact pad in one rotational direction to enable said one contact padto grip said shank between it and said other contact pad whereby even inthe absence of a clamping force said clamping jaw retains itself in afixed position on said shank.
 5. A clamping jaw as claimed in claim 1wherein said guide means comprises a link pivoted at one end thereof tothe jaw member and at the other end thereof to the second contact pad tocontrol the movement of the second contact pad with respect to the jawmember.
 6. A clamping jaw as claimed in claim 5 in which the firstcontact pad is pivoted to the jaw member and in which the link ispivoted to the pivotal axis of the first contact pad.
 7. A clampingassembly comprising a shank and two clamping jaws for sliding along saidshank to desired clamping locations and then engaging with said shankand exerting a clamping force which is reacted through said shank, eachof said jaws comprising: an elongated jaw member, a clamping pad securedat one end portion of said jaw member for exerting a clamping force on awork piece in one longitudinal Direction of said shank, a first contactpad and a second contact pad carried at the opposite end portion of saidjaw member, said contact pads defining between them a shank receivingspace, a surface of said first contact pad being arranged for frictionalengagement with a side of said shank asjacent said clamping pad and saidsecond contact pad being arranged for frictional engagement with theside of said shank remote from said clamping pad at a position alongsaid shank in the direction of said clamping force from said firstcontact pad, one of said contact pads being mounted on said jaw memberfor pivotal movement about an axis fixed with respect to said jawmember, and the other of said contact pads being movably mounted on saidjaw member, means for being connected between said other of said contactpads and said jaw member for moving said other of said contact padsrelative to said jaw member in a direction towards said shank and thuspivoting said jaw member with respect to said shank for applyingclamping force to said work piece, said jaw member pivoting about saidaxis about which said one of said contact pads is mounted for pivotingwith respect to said jaw member, said clamping pad of each of said jawsincluding a work engaging portion, said clamping pad being pivotallyconnected to the jaw member for movement about an axis transverse to thelength of the jaw member and to the length of the shank and said workengaging portion being rotatable with respect to said clamping pad.